This invention relates to the production of glass fibers, and in particular, to winding a glass fiber strand to form packages. More particularly, this invention relates to a method and apparatus of building multiple packages on a single collet.
Mineral fibers are used in a variety of products. The fibers can be used as reinforcements in products such as plastic matrices, reinforced paper and tape, and woven products. During the fiber forming and collecting process numerous fibers are bundled together as a strand. Several strands can be gathered together to form a roving used to reinforce a plastic matrix to provide structural support to products such as molded plastic products. The strands can also be woven to form a fabric, or can be collected in a random pattern as a fabric. The individual strands are formed from a collection of glass fibers, or can be comprised of fibers of other materials such as other mineral materials or organic polymer materials. A protective coating, or size, is applied to the fibers which allows them to move past each other without breaking when the fibers are collected to form a single strand. The size also improves the bond between the strands and the plastic matrix. The size may also include bonding agents which allow the fibers to stick together, thereby forming an integral strand. It is to be understood that the use of a size is optional.
Typically, continuous fibers, such as glass fibers, are mechanically pulled from a feeder of molten glass. The feeder has a bottom plate, or bushing, which has anywhere from 200 to 10,000 orifices. In the forming process, the strand is wound around a rotating drum, or collet, to form, or build, a package. The completed package consists of a single long strand. It is preferable that the package be wound in a manner which enables the strand to be easily unwound, or paid out. It has been found that a winding pattern consisting of a series of helical courses laid on the collet builds a package which can easily be paid out. Such a helical pattern prevents adjacent loops or wraps of strand from fusing together should the strand be still wet from the application of the size material. The helical courses are wound around the collet as the package begins to build. Successive courses are laid on the outer surface of the package, continually increasing the package diameter, until the winding is completed and the package is removed from the collet.
A strand reciprocator guides the strand longitudinally back and forth across the outer surface of the package to lay each successive course. A known strand reciprocator is the spiral wire type strand oscillator. It consists of a rotating shaft containing two outboard wires approximating a spiral configuration. The spiral wires strike the advancing strand and direct it back and forth along the outer surface of the package. The shaft is also moved longitudinally so that the rotating spiral wires are traversed across the package surface to lay the strand on the package surface. While building the package, the spiral wire strand oscillator does not contact the package surface. Although the spiral wire strand oscillator produces a package that can be easily paid out, the package does not have square edges.
A known strand reciprocator which produces square edged, cylindrical packages includes a cam having a helical groove, a cam follower which is disposed within the groove and a strand guide attached to the cam follower. As the cam is rotated, the cam follower and strand guide move the strand longitudinally back and forth across the outer surface of the rotating package to lay each successive course. A rotatable cylindrical member, or roller bail, contacts the outer surface of the package as it is being built to hold the strand laid in the latest course in place at the package edges as the strand guide changes direction. The roller bail is mounted for rotation, and bearings are used to reduce the friction between the roller bail and the mounting surface. The collet and package are rotating at high speeds during winding. The contact between the roller bail and the rotating package surface causes the roller bail to rotate, and the speed of the roller bail surface is generally equal to the high rotational speed of the package surface. The roller bail has a fixed diameter which is generally less than the diameter of the collet, and may be only 10% of the collet diameter. Therefore, the roller bail must rotate at higher revolutions per minute (RPMs) to keep the roller bail surface traveling at the same speed as the speed of the package surface. To operate effectively throughout the preferred range of package sizes and preferred collet speeds during winding the roller bail may have to rotate at 70,000 RPMs or higher.
The rotating rollers of the roller bails contact the strand as it is laid on the package surface. If the speed of the roller bail surface does not match the speed of the package surface, the roller bail will apply abrasive forces against the strand, and this can break some of the fibers in the strand. Bearings are provided between the roller bail mounts and the rotating roller bail to reduce friction and allow the roller bail to rotate at high RPMs. Typical grease lubricated bearings which have been used in the past have been found not to reduce the friction enough to allow the roller bails to operate at such high RPMs without causing abrasive forces against the strand which can break strand fibers. The strand reciprocator has other moving parts in addition to the roller bails with surfaces which need lubrication. The rotating cam has bearings which use lubrication. The cam follower needs lubrication while it moves along the groove on the cam surface.
Several attempts have been made to form multiple packages on a single collet. For example, U.S. Pat. No. 2,204,475 to Crandall discloses making multiple packages on cores 19 that are temporarily attached to sleeve 3. The sleeve is slid onto the spindle, and the sleeve is indexed one groove at a time to wind the packages one groove at a time. Then, the entire sleeve is removed. However, Crandall does not disclose a cam or builder, and the sleeve on which packages are built is moved or indexed for each package.
U.S. Pat. No. 3,334,980 to Smith discloses two forming packages on one spindle. However, the packages that are formed have tapered ends and not substantially square edges.
U.S. Pat. No. 2,207,615 to Crandall discloses multiple packages on a single sleeve. The packages are square edged. Successive cores are successively moved past the package building position. During changeover from one package to the next the guide is removed from contact with the package. Crandall""s several embodiments all call for multiple guides (i.e., cams or builders) to accommodate several packages, or indexing of the cores to build successive packages at the same operating or building position.
U.S. Pat. No. 4,784,341 to Hill et al. discloses a thread winding apparatus where two successive spools of thread are wound. A guide 2 has opposed fingers 18, 20 for guiding the thread. A cam 6 on threaded rod 4 reciprocates the guide left and right. The motor driving the threaded rod reverses itself as the guide reaches each end of the spool. Upon completion of the first package shown in FIG. 1 the cam is lifted out of contact with the threaded rod and the cam and guide are moved axially to the right or outward direction to be in position to wind the next spool of thread. However, Hill""s packages are not square-edged, but rather are maintained in their form by virtue of the sides or rims of the spool. Further, the fingers 18, 20 of the guide merely guide the thread in a reciprocal fashion. In addition, the reciprocation in Hill is accomplished by the reversal of the rotational direction of the threaded rod 4.
It has been found that the interruption of attenuation of the strands at the completion of each package results in instabilities at the stream feeder or bushing with the formation of each package. Each interruption of attenuation to doff the package and apply an empty tube or collector to the mandrel involves reducing high speed linear attenuation of the strands. During this reduction of speed the strands become non-uniform in diameter, resulting in fiber that must be scrapped. Also, after doffing, while the collet and collector are brought up to proper attenuating speed, the attenuated strands are of non-uniform diameter, and these fibers must also be scrapped. Thus, it would be desirable to provide a method and apparatus for successively winding multiple separate packages of strand mounted in end-to-end relationship on a single collet. Preferably the transfer of the strand from one package position to another can be accomplished without the interruption of attenuation that normally occurs when the winding of one package is completed and the transfer of the strand is effected to build another package.
The above objects as well as other objects not specifically enumerated are achieved by a method of building multiple wound packages of strand on a collet, the method comprising the steps of providing a collet, supplying a continuous strand to the collet, and rotating the collet to wind the strand to build a first package at a first location on the collet. The strand is reciprocated from one end of the package to the other end of the package using a strand reciprocator that includes a rotating cam and a cam follower having a stand guide. The strand is reciprocated from the one end to the other end as the package rotates, thereby forming strand courses. The strand courses are held in place at edge portions of the package as the strand guide changes direction to make a square edged package. At the completion of the first package the strand is transferred to a second location on the collet so that a second package can be built at the second location. The strand transfer includes moving the strand reciprocator away from the collet, directing the strand from the first location to the second location, and moving the strand reciprocator into engagement with the collet to build a second package at the second location.
According to this invention, there is also provided a method of building multiple wound packages of strand on a collet, the method comprising the steps of providing a collet, supplying a continuous strand to the collet, and rotating the collet to wind the strand to build a first package at a first location on the collet. The strand is reciprocated from one end of the package to the other end of the package using a strand reciprocator that includes a rotating cam and a cam follower having a strand guide. The strand reciprocator reciprocates the strand from the one end to the other end as the package rotates, thereby forming strand courses. The strand courses are held in place at edge portions of the package as the strand guide changes direction to make a square edged package. At the completion of the first package the strand is transferred to a second location on the collet so that a second package can be built at the second location. The strand transfer includes moving the strand reciprocator away from the collet and directing the strand from the first location to the second location by engaging the strand with a strand positioner. The strand positioner is moved laterally along the direction of the length of the collet to move the strand to the second location. The strand is disengaged from the strand positioner. The secondary shoe and strand positioner are controlled with a controller during the movement of the strand from one package location to another package location. The strand reciprocator is then moved into engagement with the collet to build a second package at the second location.
According to this invention, there is also provided apparatus for building multiple packages on a collet, comprising a rotatable collet, a primary shoe located upstream of the collet for forming a fibrous strand, and a secondary shoe for directing the strand to the collet. A strand positioner is mounted for movement toward the strand for engagement with the strand and away from the strand for disengagement with the strand. The strand positioner is adapted to position the strand at multiple package locations on the collet to enable building a package at each of the package locations. A strand reciprocator includes a rotating cam and a cam follower having a strand guide. Rotation of the cam reciprocates the strand from one end of the package to the other end of the package as the collet rotates, thereby enabling the strand to be wound on the collet in courses. A roller bail holds the strand courses in place at edge portions of the package as the strand guide changes direction to make a square edged package. The secondary shoe and strand positioner can be operated to move the strand from one package location to another package location on the collet.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.